You have a LUN that needs to be added via raw mapping to a VM in ESXi. This is often done to access a LUN on a SAN or iSCSI NAS that is already formatted as Windows NTFS, Linux ext3, etc. It’s a type of “pass-through” LUN that you would map to VMware and then into a VM.
BE CAREFUL! Many filesystems, e.g., NTFS, can only be used by one computer at a time! If you open an NTFS volume on two Windows computers at once you will most likely permanently destroy that NTFS volume!
You can do this in vSphere Client.
- In vSphere Client, choose the VM to add the RAW LUN mapping and click Edit virtual machine settings
- On the Virtual Machine Properties page Hardware tab, click Add… Under Device Type, choose Hard Disk and click Next
- Click the Raw Device Mappings option and click Next (If this option is greyed out, see the note at the end of this post)
- Choose the LUN you wish to map and click Next
- Choose where the RDM will be stored, with the Virtual Machine is default. Click Next
- Choose the compatibility mode for the disk and click Next
- Choose the controller type and node, then click Next
- Click Finish
- Back at the Properties page, click OK
- Wait for the task to complete successfully
- Log in and verify your HDD is usable
- For Dell MD32xx SAS Storage Arrays, the RdmFilter.HbaShared checkbox must be deselected on your ESXi host:
- For other potential causes and resolutions for a grayed out RDM option, please refer to VMWare KB 1017704: